Hyperon and Charged Kaon Pair Production close to Threshold

Abstract

Close to threshold data on the elementary kaon and antikaon
production channels in the proton-proton interaction have
been taken using the COSY-11 installation at the cooler
synchrotron COSY Jülich.
The experimental technique applied at the internal COSY-11
facility -
designed for meson production studies at small excess energies -
is outlined.
The threshold excitation functions for the kaon-hyperon
production via the reactions
pp->pK+Lambda and
pp->pK+Sigma0 are
presented.
The magnitude of the production amplitudes is compared at equal
excess energies and physical implications of the observed
Sigma0 suppression in the threshold region
are discussed [1].
In addition, within a Dalitz plot analysis the spin-averaged
S-wave scattering parameters could be extracted for the
Lambda-p channel [2].
With the possibility of detecting all final state particles
the elementary antikaon production in the reaction
pp->ppK+K- has been
investigated [3,4].
Results on the exclusive total cross section fix the scale
of the strangeness dissociation into two kaons and are compared
to existing parametrizations and model calculations.